Author: Jianzhou Zhao Date: 2021-01-13T01:22:05Z New Revision: 82655c151450e0103a3aa60725639da607f9220c
URL: https://github.com/llvm/llvm-project/commit/82655c151450e0103a3aa60725639da607f9220c DIFF: https://github.com/llvm/llvm-project/commit/82655c151450e0103a3aa60725639da607f9220c.diff LOG: [MSan] Tweak CopyOrigin There could be some mis-alignments when copying origins not aligned. I believe inaligned memcpy is rare so the cases do not matter too much in practice. 1) About the change at line 50 Let dst be (void*)5, then d=5, beg=4 so we need to write 3 (4+4-5) bytes from 5 to 7. 2) About the change around line 77. Let dst be (void*)5, because of lines 50-55, the bytes from 5-7 were already writen. So the aligned copy is from 8. Reviewed-by: eugenis Differential Revision: https://reviews.llvm.org/D94552 Added: Modified: compiler-rt/lib/msan/msan_poisoning.cpp Removed: ################################################################################ diff --git a/compiler-rt/lib/msan/msan_poisoning.cpp b/compiler-rt/lib/msan/msan_poisoning.cpp index ef3c74e0a35a..8f58432d528a 100644 --- a/compiler-rt/lib/msan/msan_poisoning.cpp +++ b/compiler-rt/lib/msan/msan_poisoning.cpp @@ -47,7 +47,7 @@ void CopyOrigin(const void *dst, const void *src, uptr size, uptr beg = d & ~3UL; // Copy left unaligned origin if that memory is poisoned. if (beg < d) { - u32 o = GetOriginIfPoisoned((uptr)src, d - beg); + u32 o = GetOriginIfPoisoned((uptr)src, beg + 4 - d); if (o) { if (__msan_get_track_origins() > 1) o = ChainOrigin(o, stack); *(u32 *)MEM_TO_ORIGIN(beg) = o; @@ -71,12 +71,13 @@ void CopyOrigin(const void *dst, const void *src, uptr size, if (beg < end) { // Align src up. uptr s = ((uptr)src + 3) & ~3UL; + uptr aligned_beg = ((uptr)dst + 3) & ~3UL; // FIXME: factor out to msan_copy_origin_aligned if (__msan_get_track_origins() > 1) { u32 *src = (u32 *)MEM_TO_ORIGIN(s); u32 *src_s = (u32 *)MEM_TO_SHADOW(s); - u32 *src_end = (u32 *)MEM_TO_ORIGIN(s + (end - beg)); - u32 *dst = (u32 *)MEM_TO_ORIGIN(beg); + u32 *src_end = (u32 *)MEM_TO_ORIGIN(s + (end - aligned_beg)); + u32 *dst = (u32 *)MEM_TO_ORIGIN(aligned_beg); u32 src_o = 0; u32 dst_o = 0; for (; src < src_end; ++src, ++src_s, ++dst) { @@ -88,8 +89,9 @@ void CopyOrigin(const void *dst, const void *src, uptr size, *dst = dst_o; } } else { - REAL(memcpy)((void *)MEM_TO_ORIGIN(beg), (void *)MEM_TO_ORIGIN(s), - end - beg); + REAL(memcpy) + ((void *)MEM_TO_ORIGIN(aligned_beg), (void *)MEM_TO_ORIGIN(s), + end - aligned_beg); } } } _______________________________________________ llvm-branch-commits mailing list llvm-branch-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
